1. Field of the Invention
The present invention refers to an improved kind of refrigeration apparatus provided with means for carrying out a fresh-food refrigeration program, which is caused to automatically vary in accordance with the nature of the food products to be deep-frozen. In particular, the present invention is adapted to identify the nature of the freezing load based on the temperature detected inside the refrigeration compartment in response to the temperature detected by an appropriate device at the core of the freezing load itself during the first phases of the freezing process, as well as to adapt the phases of the freezing process in accordance with the temperature response.
2. Description of the Related Art
Although reference will solely be made to a refrigeration apparatus of the kind intended for use in food-service operations, and provided with a single refrigeration compartment, throughout the following description, what is going to be explained and illustrated hereinbelow shall be appreciated to readily and similarly apply to combination refrigerator-freezer appliances or appliances provided with a plurality of compartments at different temperatures.
In professional food-service operations, such as restaurants, public houses, and the like, a large use is generally made of considerable amounts of products that must be deep-frozen and kept stored under freezing conditions for relatively long periods of time. However, since these food products in this particular field of application are usually processed in volumes and amounts that are certainly far more substantial than they are at home, it ensues that the deep-freezers that are capable of handling such considerable food volumes, are not generally found to be capable of equally ensuring any adequate refrigeration capacity in view of deep-freezing the food products within the maximum time allowances provided for by the applicable standard regulations.
It would of course be fully possible for large-volume deep-freezers to be provided so as to also feature an adequate refrigeration capacity; such appliances would however prove expensive to quite an unacceptable extent. In view of solving this problem, use is therefore largely made in the food-service industry of deep-freezing appliances of a particular kind, i.e. the so-called chillers, which are provided with a high freezing capacity, actually, but are relatively limited in the useful freezing volumes they generally offer. The use of these chillers is practically aimed at pulling down the temperature of the food products placed thereinside in a very quick manner, so as to have the food products frozen well within the time allowances provided for and in the proper ways as required by the standard regulations. Upon having so been deep-frozen in the chillers, the just frozen food products are removed from the same chillers and placed in the low-temperature storage compartments of regular freezers which, while affording large storage volumes, are in this way not required to provide any particularly high freezing capacity, since the food products stored therein are already in a deep-frozen state.
Incidentally, these chillers are also used to abruptly pull down the temperature of food products, which are either fresh food items or food items that have been just cooked, which do not require being deep-frozen, but just cooled down in a quick manner in view of being able to be preserved for just a few days.
When used to this particular purpose, however, these chillers have a major drawback—largely known as such in the art—lying in the fact that—owing to the required temperature pull-down rapidity—the quick temperature decrease effect that they generally bring about inside, i.e. at the core of the food products themselves, and which is measured with a so-called core-temperature probe in the form of a special needle-like stick carrying a temperature sensor at the tip thereof for introduction in the food product, causes the temperature in the storage compartment to equally decrease to very low values in a correspondingly quick manner. Such an occurrence comes to exist even if the final temperature of the food product—as measured by the core-temperature probe—does in no case decrease below zero, since the cooling-down process is stopped before this can happen.
However, owing exactly to its being pulled down in a quick manner to a very low value, the temperature prevailing in the chilling compartment gives rise to the occurrence of the well-known surface “blackening” effect, in which the surface or outside layers of the food products are practically frozen down, even if the core temperature thereof remains at clearly higher values. This freezing effect is due to the fact that, owing to the temperature in the chilling compartment being very low, the surface layers of the food products placed therein are ultimately conditioned by such temperature since they have quite limited a heat capacity towards the outside and, moreover, act as heat insulators towards the innermost layers of the same food products, which of course keep at quite higher a temperature value while undergoing a much slower temperature pull-down process that is anyway interrupted well in advance of such inner layers being able to freeze.
As this can readily be appreciated, such negative surface “blackening” occurrence has a rather spoiling effect of the food products affected and tends to show up particularly in food products with a high water content or a smaller heat capacity—and which are therefore particularly delicate—as this is the case with almost all fresh vegetables; in addition, in the case of many sweet-meats and articles of confectionary in general there frequently forms a surface layer of frost or ice that, when eventually thawing out, tends to produce a “wash-out” effect and, as a result, spoil the surface layers of such products to the obvious detriment of both the quality and the appearance thereof.